1. Field of the Invention
The present invention relates to golf. More particularly, the present invention relates to a set of iron-type golf clubs.
2. Description of the Related Art and Summary of the Invention
A typical set of golf clubs includes a set of wood-type clubs for hitting the ball off the tee and for long shots, a set of iron-type clubs for long, medium, and short shots, and a putter to roll the ball on the green. Of all the clubs in a set, the iron-type clubs, or "irons," typically encounter the most variations in shot distances and the most variations in ground, obstacle and lie conditions.
The irons are numbered with designations from 1 through 9 and with individual wedge designations. For example, the iron which could essentially be designated number 10 is designated PW (pitching wedge). Additional wedges are often provided to provide even greater loft to the ball than a pitching wedge. Within a set, the higher the number designation, the greater the loft of the club. The lower numbered or long irons hit the ball the longest distance and are the most difficult to play, as it is relatively hard for the average golfer to get the ball airborne with the long irons. Golf club manufacturers thus try to design long irons that are easier to hit and more forgiving of off-centered shots. The medium numbered irons hit the ball a medium distance. The medium irons are typically designed to be both easy to hit and accurate. The shortest irons hit the ball the shortest distance and are used to land the ball closer to the target. As the location where the ball lands on the green is critical, more controllability and precision over the ball is required for the short irons. For the average golfer it is much easier to get the ball airborne with the short irons than with the long irons.
Unlike woods and putters, golfers typically purchase the irons as a correlated set which includes a large range of clubs. The clubs in such a set are designed to work together to reliably provide a golfer with predictable and progressive increments in shot distance from the lower numbered clubs to the higher numbered clubs. For example, a certain golfer may hit the ball 150 yards using the 7 iron, 160 yard using the 6 iron, 170 yards using the 5 iron, and so on. Thus, a golfer playing with a correlated set of irons may choose with confidence the iron that is most suited for the particular shot type and shot distance being encountered. This is not necessarily true with a random collection of irons where the incremental difference in shot distance between the clubs may not be coordinated.
Additionally, each of the clubs in a correlated set typically share a consistent look, such as consistent markings, color combinations, or the type of polishing or texture of the club head and shaft. Although the common features do not necessarily affect the playability of the clubs, golfers generally feel most comfortable when playing with a correlated set of irons, rather than with a group of irons that was randomly collected. A correlated set of irons thus contributes to the important mental aspects of a golfer's game by increasing the golfer's confidence when hitting the ball.
Golf club manufacturers progressively vary certain standard structural features of the irons in a correlated set to achieve the difference in ball distance from the lower numbered to the higher numbered clubs. For example, the loft angle of the clubs, which is the angle between a vertical plane passing through the shaft axis and a plane passing through the strike surface of the club head, progressively increases moving from the long irons to the short irons. The greater loft angle in the short irons gives these irons an increased tendency to lift the ball upon impact so that the ball travels a shorter distance. Another standard structural feature that is varied is the length of the club shaft, which decreases moving from the long clubs to the short clubs. The lie angles of the irons are also varied to accommodate the different lengths of shafts throughout the complete set of iron clubs.
U.S. Pat. Nos. 5,480,145, 5,665,009, and 5,388,826 to Sherwood disclose a correlated set of golf clubs having features that vary progressively from the lower numbered clubs to the higher numbered clubs. For example, the long irons have a larger planar strike area than the shorter irons to increase the size of the sweet spot for the long irons. These patents also disclose that the size of the rear cavity on the irons may decrease as the club shaft becomes shorter.
While manufacturers have varied the aforementioned features throughout the clubs in a single set of irons, there are also certain fundamental or basic design characteristics that have conventionally remained constant or homogeneous throughout all of the clubs in a coordinated, conventional set of irons. For example, one correlated set of irons may have a "cavity back" design wherein all of the clubs in the set have a cavity on the rear face of the club head. The cavity promotes a peripheral distribution of mass to increase the size of the sweet spot of the club and thereby makes the club easier to hit. Another correlated set of irons may have a "blade" design wherein all of the club heads generally are in the shape of a flattened blade. The blade design concentrates more mass directly behind the ball for a more solid and more controllable shot than the cavity-back irons. Specifically, a blade design provides the golfer with greater feedback to enable the golfer to more precisely alter a stroke to achieve the desired results. Thus, the cavity-back type of irons generally provide a more forgiving, although less controllable, shot than blade-type irons.
Yet another basic design characteristic that typically remains constant throughout all of the clubs in a coordinated, conventional set of irons is the material that is used to manufacture the club heads. For example, one correlated set of irons may comprise heads manufactured of titanium, which is a strong, lightweight material. Unfortunately, a set of titanium clubs is extremely expensive because of the high cost of titanium. Another correlated set of iron clubs may have heads that are manufactured of steel. A set of steel clubs is less expensive than titanium clubs.
Unfortunately, the performance of the specific clubs in a set may be adversely affected if all of the clubs include the same basic design characteristics. For example, the increased precision of the blade design may not be optimal for the long irons, where the emphasis should be toward enhancing the playability of the clubs by making it easier to get the ball airborne. Likewise, the cavity-back design is not necessarily suited for the shortest irons, which should emphasize feel and feedback and, therefore, controllability of the ball.
Additionally, the material used to manufacture the club head should not necessarily be consistent throughout all of the clubs in a correlated set. The use of light-weight titanium is highly suited for the longer irons, where the weight savings allows the club head to be made larger to increase the size of the sweet spot. However, using titanium may be inefficient and unnecessarily costly for the shorter irons, where controllability of the ball, rather than weight savings, is emphasized.
The design characteristics of the clubs should be specifically directed toward improving the specific playing needs of each of the clubs or groups of clubs in the set. For example, the properties of easy playability and forgiveness should be promoted for the long irons. The property of controllability of the shot should be promoted for the short irons. The middle irons should preferably be designed to compromise between playability and precision. These objectives are not necessarily accomplished if the clubs in a correlated set are united by a single, basic design characteristic.
There is therefore a need for a correlated set of golf clubs wherein each club or a group of clubs in the set utilizes technology that is specifically designed to promote the playing needs of that particular type of club.
In one aspect of the invention, there is disclosed a correlated set of golf clubs, comprising at least a first iron having a first club head. The first club head has a first loft designation and a first center of gravity located a first vertical distance from the ground plane when the club head is in address position. The set also comprises a second iron having a second club head. The second club head has a second loft designation designating a higher loft than the first loft designation and a second center of gravity located a second vertical distance from the ground plane when the club head is in address position. The second vertical distance is longer than the first vertical distance. The set further comprises a third iron having a third club head, the third club head having a third loft designation designating a higher loft than the second loft designation and a third center of gravity located a third vertical distance from the ground plane when the club head is in address position. The third vertical distance is longer than the second vertical distance.
Another aspect of the invention relates to a correlated set of golf clubs. The set comprises a first iron having a first club head, the first club head having a loft designation "3" and a first center of gravity located a first vertical distance from the ground plane when the club head is in address position; a second iron having a second club head, the second club head having a loft designation of one of "2" and "4" and a second center of gravity located a second vertical distance from the ground plane when the club head is in address position; a third iron having a third club head, the third club head having a loft designation of "5" and a third center of gravity located a third vertical distance from the ground plane when the club head is in address position; and a fourth iron having a fourth club head, the fourth club head having a loft designation of one of "4" and "6" and a fourth center of gravity located a fourth vertical distance from the ground plane when the club head is in address position. Each of the club heads have a unique loft designation and the first vertical distance is shorter than either of the third vertical distance and the fourth vertical distance. Additionally, the second vertical distance is shorter than either of the third vertical distance and the fourth vertical distance.
In yet another aspect of the invention, there is disclosed a correlated set of golf clubs, comprising a first iron having a first club head, the first club head having a loft designation "3" and a first center of gravity located a first vertical distance from the ground plane when the club head is in address position; a second iron having a second club head, the second club head having a loft designation "4" and a second center of gravity located a second vertical distance from the ground plane when the club head is in address position; a third iron having a third club head, the third club head having a loft designation of "5" and a third center of gravity located a third vertical distance from the ground plane when the club head is in address position; a fourth iron having a fourth club head, the fourth club head having a loft designation "6" and a fourth center of gravity located a fourth vertical distance from the ground plane when the club head is in address position; a fifth iron having a fifth club head, the fifth club head having a loft designation "7" and a fifth center of gravity located a fifth vertical distance from the ground plane when the club head is in address position, wherein none of the loft designations are identical and the first vertical distance is shorter than the fifth vertical distance, and the second vertical distance is shorter than the fifth vertical distance; and a sixth iron having a sixth club head, the sixth club head having a loft designation "8" and a sixth center of gravity located a sixth vertical distance from the ground plane when the club head is in address position. Each of the first vertical distance, the second vertical distance, the third vertical distance and the fourth vertical distance are at least as short as each of the fifth vertical distance and the sixth vertical distance.
In yet another aspect of the invention, there is disclosed a set of golf clubs comprising at least a first group of golf clubs, wherein each of the clubs in the first group comprises a club head having a main body of a first material having a first density; and at least a second group of golf clubs, wherein each of the clubs in the second group comprises a club head having a main body of a second material having a second density higher than the first density, wherein the first group of clubs comprise lower numbered clubs than the second group of clubs. Desirably, each of the clubs heads of the first group of clubs comprises a face, a sole, and a rear cavity surrounded by a peripheral belt of mass, and a separate weight insert of material having a higher density than the first density. The weight insert is positioned on a lower portion of the peripheral belt of mass so as to shift the center of gravity of the each of the club heads of the first group toward the sole. Each of the heads of the second group of clubs comprises a face, a sole, and a rear cavity surrounded by a unitary peripheral belt of mass.
In one embodiment, each of the club heads in the second group is made entirely of a single piece of the same type of one of metal and metal alloy. Each of the club heads of the second group includes at least one weight insert positioned on a lower portion of the peripheral belt of mass of the club heads of the second group. The weight inserts of the club heads of the first and second groups group are positioned below annular surfaces surrounding the rear cavities of the club heads.
In one embodiment, each of the club heads of the second group further comprises a separate face insert. The face insert of each of the club heads of the second group is manufactured of titanium. In another embodiment, the face insert of each of the club heads of the second group is manufactured of one of a titanium alloy, aluminum and an aluminum alloy. The at least one weight insert of each of the club heads of the second group is desirably made of a tungsten alloy. The first material mentioned above desirably comprises one of titanium and a titanium alloy, and the weight inserts of the first set of clubs are made of a tungsten-based material. The second material comprises one of steel and a steel alloy.
Another embodiment additionally comprises a third group of clubs, wherein each of the clubs in the third group comprises a club head having a face and a sole wherein the clubs of the third group have lower numbers than the clubs of the second group and wherein the clubs heads of the third group are made of higher density material than the club heads of the first group. The club heads of the third group are preferably made of steel and may have a rear cavity surrounded by a peripheral belt of mass.
The first group of clubs may comprises clubs from the set of 1, 2, 3, 4, 5, and 6 numbered clubs; the second group of clubs may comprises clubs from the set of 7, 8, and 9 numbered clubs and the pitching wedge; and the third group of clubs may comprise clubs from the set of the approach wedge, the sand wedge, and the lob wedge.
Yet another embodiment additionally comprises a fourth group of clubs having higher numbers than the clubs of the third group, wherein each of the clubs in the fourth group comprises a club head having a face and a sole and wherein the club heads of the fourth group are made of higher density material than the club heads of the first group. The club heads of the fourth group are desirably made of steel.
In one embodiment, the first group of clubs comprises clubs from the set of 1, 2, 3, 4 and 5 numbered clubs; the second group comprises clubs from the set of 6 and 7 numbered clubs; the third group comprises clubs from the set of 8 and 9 numbered clubs and a pitching wedge; and the fourth group comprises clubs from the set of the approach wedge, the sand wedge, and the lob wedge. A single piece of packaging preferably enclosing the set of golf clubs.
Yet another aspect of the invention relates to a set of golf clubs. The set comprises a first group of golf clubs, each of the first group of golf clubs having a head and a loft designation, and a second group of golf clubs, each of the second group of golf clubs having a head and a loft designation. The loft designation of each of the first group of golf clubs and each of the second group of golf clubs is unique. Additionally, each loft designation of the second group of golf clubs is higher than each loft designation of the first group of golf clubs. Each of the first group of golf clubs and the second group of golf clubs has a substantially same strike surface indicia and substantially the same loft designation typestyle. Desirably, the head of each of the first group of golf clubs differs from the head of each of the second group of golf clubs in at least one from the group of density and the existence of separate weight inserts.